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US Fleet Forces Command > Naval Oceanography > United States Naval Observatory

United States Naval Observatory


 United States Naval Observatory



                                   Welcome to the U. S. Naval Observatory



The United States Naval Observatory provides a wide range of astronomical data and products, and serves as the official source of time for the U.S. Department of Defense and a standard of time for the entire United States.


The United States Naval Observatory is a fourth echelon operational command reporting to the Commander, Navy Oceanography and Meteorology Command. The Observatory's headquarters are located in Washington, D.C., with field activities located at the Naval Observatory Flagstaff Station (NOFS) in Flagstaff, Ariz., and the USNO Alternate Master Clock located at Schriever Air Force Base near Colorado Springs, Colo.

The U.S. Naval Observatory performs an essential scientific role for the United States, the Navy, and the Department of Defense. Its mission includes determining the positions and motions of the Earth, Sun, Moon, planets, stars and other celestial objects; providing astronomical data; determining precise time; measuring the Earth's rotation; and maintaining the Master Clock for the United States. Observatory astronomers formulate the theories and conduct the relevant research necessary to improve these mission goals.

This astronomical and timing data, essential for accurate navigation and the support of communications on Earth and in Space, is vital to the Navy and Department of Defense. It is also used extensively by other agencies of the government and the public at large.

The Observatory consists of four Scientific Departments: Astrometry, Astronomical Applications, Earth Orientation, and Time Service. Each Department is responsible for specific products and services tailored to our end-users within both the DoD and civilian worlds.







  • Determine the positions and motions of celestial bodies, motions of the Earth, and precise time.
  • Provide astronomical and timing data required by the Navy and other components of the Department of Defense for navigation, precise positioning, and command, control, and communications.
  • Make these data available to other government agencies and to the general public.
  • Conduct relevant research, and perform such other functions as may be directed by higher authority.


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